Method of applying metallic coatings



3,107,175 ?atented Get. 15, 1963 3,107,175 METHQD 9F AiPLYlNG METALLHC COATINGS Arthur T. Cape, Monterey, (Iaiii, assignor to Coast Metals, lino, Little Ferry, N.E., a corporation of Detaware No Drawing. Filed Get. 2, 1961, Ser. No. 142,020 1 Qiaim. (Cl. 117-130} This invention relates generally to methods of applying metallic coatings, but has reference more particularly to the production of metallic coatings on articles by chemical methods.

In accordance with the invention, a mixture of aluminum powder and nickel fluoride, in the proportions of 40 to 60 parts by weight of aluminum to 60 to 40- parts by weight of the fluoride, is placed, in a thin layer, on a part, as for example, a part made of stainless steel, super alloys, etc., and the article is heated to a temperature within the range of from about 1950 F. to about 2050 F., for about one hour.

This produces a reaction, as a result of which a layer or coating is formed on the article, consisting of an alloy of nickel and aluminum, having a thickness of from about 0.0007 inch up to about 0.0035 inch, which coating is highly resistant to oxidation.

The time or period of heating has some influence on the nature and thickness of the coating formed, and this may be varied from about /2 hour to about 1 /2 hours.

To facilitate application of the aforesaid mixture to the article, the mixture may be formed into a paste, using a binder of an acrylic resin or other suitable binder, which disappears during the reaction, and does not therefore enter into the reaction.

If it is desired that the coating contain some chromium, the mixture can contain, in a desired amount, chromium fluoride, chromium difluoride or chromium trifluoride, in addition to, or in substitution for, the nickel fluoride.

If it is desired that the coating contain some cobalt, the mixture can contain, in a desired amount, a cobalt fluoride, in addition to, or in substitution for, the nickel fluoride.

In most cases, the adherence of the alloy coating to the article is greatly aided by applying .to the article, before the mixture is applied, a plating or thin layer of gold or platinum.

The reactions, in all cases, tend to be exothermic.

It is to be understood that various changes can be made in the method, as described, without departing from the scope of the appended claim.

Having thus described my invention, I claim:

The method of forming an alloy coating on a metallic article, which consists in applying to the article a mixture containing from about to parts by weight of aluminum powder, and from 60 to 40 parts by weight of one or more fluorides, selected from the group consisting of nickel fluoride, chromium fluoride, chromium difiuoride, chromium trifluoride, and cobalt fluoride, and heating the article to 'a temperature within the range of from about 1950 F. to about 2050 F., for a period of from about /2 hour to about 1 /2 hours to produce a reaction in which a layer of an alloy is formed on the article, said alloy consisting of aluminum and at least one element selected from the group consisting of nickel, chromium and cobalt.

References Cited in the file of this patent UNITED STATES PATENTS 2,463,342 Wiczer Mar. 1, 1949 2,496,971 Wiczer Feb. 5, 1950 2,905,549 Taylor et a1 Sept. 22, 1959 3,012,903 Cape Dec. 12, 1961 

